An Illinois appellate court on Monday threw former White House chief of staff Rahm Emanuel off the ballot for Chicago mayor because he didn't live in the city in the year before the election.

M. Spencer Green, The Associated PressFormer President Bill Clinton, left, appears at a rally for Chicago mayoral candidate and former White House chief of staff Rahm Emanuel last week in Chicago. Emanuel is vying to succeed the retiring Mayor Richard Daley but was thrown off the ballot Monday by an Illinois appellate court. The election is Feb. 22.

The decision put Emanuel's candidacy into doubt a month before the election. He had been considered the front-runner and had raised more money than any other candidate.

The court voted 2-1 to overturn a lower-court ruling that would have kept Emanuel's name on the Feb. 22 ballot.

A lawyer for Emanuel says they plan to appeal the matter to the Illinois Supreme Court.

Those challenging Emanuel's candidacy have argued that the Democrat doesn't meet the one-year residency requirement because he rented out his Chicago home and moved his family to Washington to work for President Barack Obama for nearly two years.

Emanuel has said he always intended to return to Chicago and was only living in Washington at the request of the president.

Emanuel is one of several candidates vying to replace Chicago Mayor Richard Daley, who did not seek a seventh term. Emanuel moved back to Chicago in October after he quit working for Obama to campaign full-time.

Before Monday's ruling, attorney Burt Odelson, who represents two voters objecting to Emanuel's candidacy, had little luck trying to keep Emanuel off the ballot. The Chicago Board of Election Commissioners and a Cook County judge have both ruled in favor of Emanuel, a former congressman, saying he didn't abandon his Chicago residency when he went to work at the White House.

Odelson had said he planned to take the challenge all the way to the state Supreme Court, if necessary.

The three main other candidates running for mayor are former Sen. Carol Moseley Braun, former schools President Gery Chico and City Clerk Miguel del Valle.

Braun's campaign did not immediately return a message seeking comment.